A semiconductor light emitting device chip e.g. LED chip is generally manufactured by manufacturing an epitaxial wafer for LEDs obtained by sequentially layering and growing a first semiconductor layer, light emitting semiconductor layer and second semiconductor layer that are of light emitting diode structure on a wafer for LEDs, subsequently forming electrodes respectively on the second semiconductor layer and first semiconductor layer, and making a chip. Then, emitted light generated due to recombination of a hole and an electron injected from respective semiconductor layers is extracted to the outside of the LED chip, and the light emission of the LED is visually identified. In addition, generally adopted is the structure where the emitted light is extracted from the transparent electrode side on the second semiconductor layer or the wafer for LEDs side, and it is also possible to remove the wafer for LEDs to extract the emitted light from the first semiconductor layer side.
As factors to determine external quantum efficiency EQE indicative of efficiency of an LED, there is electron injection efficiency EIE, internal quantum efficiency IQE, and light extraction efficiency LEE. Among the factors, the internal quantum efficiency IQE is dependent on the dislocation density caused by lattice mismatch of the semiconductor crystal (for example, Non-patent Document 1). The light extraction efficiency LEE is improved by disturbing the waveguide mode inside the semiconductor layer by light scattering due to an uneven structure provided on the pattern wafer for LEDs (for example, Patent Document 1). Further, the electron injection efficiency EIE is improved by reducing interface resistance between the second semiconductor layer and the transparent conductive comprised of oxide such as ITO, ZnO, In2O3, and SnO2.
The external quantum efficiency EQE of an LED is determined by three factors as described above, and the internal quantum efficiency IQE means efficiency itself that the LED emits light, and is not expected to undergo significant improvements when the first semiconductor layer, light emitting semiconductor layer and second semiconductor layer are deposited on a pattern wafer for LEDs to manufacture the epitaxial wafer for LEDs. In other words, in order to manufacture LEDs for actualizing high external quantum efficiency EQE, it is necessary to improve at least the internal quantum efficiency IQE.
From such a background, in order to significantly improve the internal quantum efficiency IQE, proposed is an LED manufactured by depositing a semiconductor layer on an uneven structure of a pattern wafer for LEDs beforehand provided with the uneven structure on the surface of the wafer for LEDs (for example, see Non-patent Document 2).